See if it is possible to try the subs before you purchase or it you are able to return if you chose to do so. Feeling like you're missing something is likely to be exactly what will keep you in this hobby and chasing that sound forever. I think most of us are always trying to reach another plateau which we think will be better. I think once you get to the point where you feel no further improvement is possible and you stop even exploring the possibility, you have lost what most makes this a hobby- your interest, like adding more horsepower, etc. to you sports car, in making it better. Try the subs and judge for yourself -it's what makes this whole thing fun.
Subwoofer insight.
This is new territory to me. Current speakers are 2 way with frequency response of 60Hz-20KHz with +/- 2dB. Sensitivity rated as 86dB. Chance to purchase a pair of REL 7 tis. I feel like I am missing something but will have to buy the subs to try out. My basic question is this. Does this purchase sound wise? I know what I am willing to spend but do you think I will notice an appreciable improvement. I know that no one can listen through my ears but this is my first time doing this. Source is 75 watt integrated tube amp, McIntosh MA-2275. Thoughts appreciated. I am leaning towards going forward with the deal but would appreciate some feedback. Room is large and open, 28X38 feet with 9 foot ceilings. Thanks for any feedback.